⚡ The Short Answer
A "seized" engine means the internal parts no longer rotate. The crankshaft will not turn, the starter clicks or grinds, and the engine sits dead. About 80 percent of the time this traces back to one of two causes: the engine ran out of oil, or it overheated badly. Both of those wreck the bearings and scuff the cylinder walls, which is why a true seize rarely gets fixed with a $200 part. If you are not certain the engine is actually seized versus just a no-start, read our guide on the engine that will not turn over first.
💵 What It Actually Costs
There is no single price for a seized engine because the fix depends on how much internal damage happened and which path you choose. Here is the realistic spread for a typical 4 to 6 cylinder car in the US, parts plus labor:
| Repair Path | Typical Cost | When It Applies | Warranty |
|---|---|---|---|
| Free up / unstick | $300 - $1,200 | Hydrolock or stuck part caught immediately, no internal damage | Rarely any |
| Used / junkyard engine | $3,000 - $5,500 | Most common money-saver, 60K-90K mile donor | 30-90 days |
| Engine rebuild | $3,000 - $6,000 | You want to keep this exact car long-term | 12 mo / 12K mi |
| Remanufactured engine | $5,000 - $9,000 | Newer or higher-value vehicle, peace of mind | 3 yr / 100K mi |
| New crate / OEM engine | $7,000 - $12,000+ | Specialty, performance, or near-new vehicle | Full factory |
Notice the used engine swap is almost always the cheapest real fix. A donor engine with 70,000 miles dropped in for around $4,000 is the path most owners take when the car is otherwise worth keeping. The unstick path looks cheap, but it only works in the small minority of cases where the engine seized without grinding its bearings, which usually means a hydrolocked engine from driving through deep water.
📊 The Repair-vs-Value Math
The decision is genuinely just arithmetic. Get your car's running value from a valuation tool using your exact year, make, model, mileage, and trim, then compare it to your repair quote. Here is how the ratio plays out:
| Repair as % of Value | Decision | Reasoning |
|---|---|---|
| Under 30% | Fix it | Cheap insurance, you keep a known car |
| 30% - 50% | Usually fix | Still cheaper than buying and financing a replacement |
| 50% - 60% | Toss-up | Depends on rest of car and your budget |
| Over 60% | Walk away | You are pouring money into a depreciating shell |
Example: your car is worth $9,000 running. A used-engine swap quote comes in at $4,200. That is 47 percent, which lands in the "usually fix" band, especially because buying a comparable replacement car means a down payment, sales tax, and new financing. Now flip it: the car is worth $4,000 and the same job costs $4,200. That is 105 percent. You would be spending more than the car is worth, so you sell it as-is for parts and move on. Before you commit either way, it is worth running the number past our repair quote checker to confirm the shop is not overcharging on labor hours.
🔎 Factors That Move the Line
The 50 to 60 percent rule is the starting point, not the whole story. These factors push you toward fixing or walking:
Reasons to fix even at a higher ratio
- The rest of the car is solid: good transmission, no rust, recent tires and brakes, no other deferred work.
- You already know the car's history and have maintained it well.
- You would otherwise buy used and inherit someone else's unknown problems.
- The model is known for 200,000-plus mile reliability, so a fresh engine buys you years.
Reasons to walk even at a lower ratio
- The transmission is also slipping or the car has frame rust. A new engine in a dying chassis is wasted money.
- The car has a salvage or rebuilt title, which caps resale even after the fix.
- High mileage everywhere else means you will be chasing the next failure soon.
- You cannot verify why it seized. If the cause was chronic low oil pressure from a worn pump, a swapped engine may meet the same fate.
⚠️ Common Mistakes That Cost People Money
- Paying to diagnose a car you would never repair. If the vehicle is worth $3,500, do not pay $200 in diagnostic time to learn the engine is seized. Assume the worst and price the walk-away.
- Trusting a verbal "rebuild" quote. Get it in writing with line items. A real rebuild includes machining, new bearings, rings, gaskets, and seals. A "rebuild" that skips machine work is a band-aid.
- Buying a used engine with no return policy. Always demand at least a 30-day warranty and ideally a compression or leak-down test on the donor. A $3,000 mistake with no recourse is the worst outcome.
- Ignoring the root cause. If the engine seized from overheating, the cooling system caused it. Find out whether you are also looking at a P0128 thermostat code or a failed water pump, or the replacement engine cooks too.
- Forgetting the trade-in floor. Even a car with a seized engine has value. Dealers and salvage buyers will pay something. Sometimes selling as-is and putting the cash toward a replacement beats repairing.
🧮 Your 4-Step Decision Framework
- Confirm it is truly seized. No crank, will not rotate by hand with a breaker bar, single clunk or dead silence. If it cranks but will not start, it is probably not seized and the math changes completely. Our free diagnosis tool helps you rule this in or out.
- Get the car's running value. Exact year, make, model, mileage, trim, and condition. This is your denominator.
- Get two written repair quotes. One for a used engine swap, one for a rebuild. Compare both to your value number.
- Apply the ratio. Under 50 percent, lean fix. Over 60 percent, lean walk. In between, let the condition of the rest of the car break the tie.